Screen lock during calls.Support

I have a Precedent, and all is well, I like the phone, but there's one glaring problem with it that annoys the ever loving p*ss out of me. As soon as I make a call, the screen immediately locks up and will go black. I'll have to hit the power button, and then unlock the screen. This is especially annoying for calls where I have to use the dial pad. Just hanging up is a task unto itself.